From: thorkill <thkr@hannover.ccc.de>
Date: Sun, 19 Jul 2015 16:53:29 +0000 (+0200)
Subject: Do not access e->to->prevedge if not defined
X-Git-Tag: release-1.1pre12~99
X-Git-Url: https://tinc-vpn.org/git/browse?p=tinc;a=commitdiff_plain;h=f75e6f61f280b138082b87ce69bdbdee3e4ba56e

Do not access e->to->prevedge if not defined

In some cases - mostly when e->to == myself the prevedge is set to NULL,
causing invalid memory access. In rare cases this may lead to malformed mst
or segfaults.
---

diff --git a/src/graph.c b/src/graph.c
index 49161c16..56ebb611 100644
--- a/src/graph.c
+++ b/src/graph.c
@@ -173,7 +173,7 @@ static void sssp_bfs(void) {
 
 			if(e->to->status.visited
 			   && (!e->to->status.indirect || indirect)
-			   && (e->to->distance != n->distance + 1 || e->weight >= e->to->prevedge->weight))
+			   && (e->to->prevedge && (e->to->distance != n->distance + 1 || e->weight >= e->to->prevedge->weight)))
 				continue;
 
 			// Only update nexthop if it doesn't increase the path length